Low-dose dobutamine echocardiography predicts the early response of dysfunctioning myocardial segments to coronary artery bypass grafting.

Dobutamine echocardiography has recently been introduced for use in identification of viable myocardium in patients with acute myocardial infarction and prediction of the response of dysfunctioning myocardial segments to coronary angioplasty. The aim of this study was to evaluate whether this test may be used to predict the early response of dysfunctioning myocardial segments to surgical revascularization. We studied 30 patients with three-vessel disease and chronic, stable angina pectoris during coronary artery bypass grafting (CABG). Patients were monitored by intraoperative transesophageal echocardiography in the transgastric short-axis view at the papillary muscle level. The left ventricle was divided into eight segments; and 240 myocardial segments were analyzed. Percentage of systolic wall thickening (PSWT) was calculated in each segment at baseline (early after pericardiectomy), before bypass during dobutamine infusion (5 micrograms/kg/min), and after separation from cardiopulmonary bypass. Segments showing PSWT < 30% at baseline were considered dysfunctional. Segments showing an increase in PSWT > 10% during dobutamine infusion were considered responders. Segments showing an increase in PSWT < 10% during dobutamine infusion were considered nonresponders. At baseline, 161 (67%) of 240 segments had PSWT < 30% (dysfunctioning segments). During dobutamine, 98 (60%) of these segments increased PSWT > 10% (from 11.3% +/- 7.6% to 24.2% +/- 12.0%, p < 0.01; responder segments), and 63 (40%) increased PSWT < 10% (from 10.2% +/- 4.9% to 8.3% +/- 5.5%, p value not significant [NS]; nonresponder segments).(ABSTRACT TRUNCATED AT 250 WORDS)

Risk factors of incomplete distribution of cardioplegic solution during coronary artery grafting.

Myocardial distribution of cardioplegic solution infused by combined antegrade/retrograde routes was assessed with myocardial contrast echocardiography in 18 patients with chronic stable angina and three-vessel disease undergoing elective coronary artery bypass grafting. Overall myocardial opacification was significantly greater in retrograde than in antegrade cardioplegia (77.7% +/- 13.4% versus 59.1% +/- 15.7%; p = 0.0009). The difference was affected by collateral circulation, as pointed out by the significant interaction between coronary collateral circulation and percent of myocardial opacification after antegrade and retrograde cardioplegia (p = 0.002). When we performed multiple comparisons, in patients with good collaterals the opacification difference between antegrade and retrograde cardioplegia was not statistically significant (66.4% +/- 10.2% versus 76.0% +/- 15.2%; p = not significant), whereas in patients with poor collaterals myocardial opacification during retrograde cardioplegia was significantly greater (44.3% +/- 15.0% versus 81.2% +/- 9.0%; p < 0.02). During antegrade cardioplegia, patients with poor collaterals showed a lower degree of myocardial opacification than patients with good collaterals (44.3% +/- 15.0% versus 66.4% +/- 10.2%; p < 0.01). Our results show that retrograde cardioplegia in patients undergoing elective coronary artery bypass grafting offers no advantage over antegrade cardioplegia when collateral circulation is well developed. On the other hand, conventional aortic root infusion may not provide adequate myocardial protection in the subset of patients with significantly narrowed or occluded coronary arteries and poor collaterals.

Papillary muscle perfusion pattern. A hypothesis for ischemic papillary muscle dysfunction.

BACKGROUND: The pathogenesis of posterior papillary muscle dysfunction is poorly understood. We hypothesized that papillary muscle perfusion pattern may explain the higher prevalence of posterior papillary muscle dysfunction after myocardial infarction. METHODS AND RESULTS: Twenty patients were monitored by transesophageal echocardiography during coronary surgery. Superselective coronary graft injections of 0.2 to 0.5 mL of sonicated albumin microbubbles were performed to assess graft patency and papillary muscle perfusion. Thirty-five graft injections were analyzed: 13 in the right coronary artery, 15 in an obtuse marginal branch, 1 in the left anterior descending coronary artery, and 6 in the first diagonal branch. The posterior papillary muscle was opacified in 16 patients, 11 from the right coronary artery and 5 from one obtuse marginal branch. In 10 of 16 patients (63%), the papillary muscle was perfused by one vessel, while in 6 of 16 (37%), it was perfused by two vessels. The anterior papillary muscle was opacified in 14 patients. Ten patients (71%) had double-vessel and 4 (29%) had single-vessel supply. In the subgroup of 10 patients with old inferior myocardial infarction, mitral regurgitation was present only among those 6 with single rather than double blood supply (P < .05). CONCLUSIONS: Myocardial infarction may cause papillary muscle dysfunction when the blood supply is provided by one rather than two vessels, as is more frequently the case with the posterior rather than the anterior papillary muscle.

Mechanisms of incomplete cardioplegia distribution during coronary artery surgery. An intraoperative transesophageal contrast echocardiography study.

BACKGROUND: Cardioplegia is used to protect the myocardium from ischemic injury during open-heart surgery. However, the delivery of cardioplegic solutions may be impaired by anatomic and/or functional conditions, such as the development of transient aortic regurgitation during antegrade administration of cardioplegia or shunting through a foramen ovale during retrograde administration. In this study, the authors used a new method of cardioplegia administration, based on intraoperative contrast echocardiography, to detect on-line causes of inadequate cardioplegia delivery. METHODS: Forty patients with coronary artery disease and a competent aortic valve, who were treated consecutively, were enrolled in this study. Patients were monitored intraoperatively by transesophageal contrast echocardiography during cardioplegia delivery. Antegrade cardioplegia was administered into the aortic root following aortic occlusion in all patients. Twenty-two patients also received retrograde cardioplegia, administered through the right atrium. The echo-contrast agent consisted of a stable suspension of 5% human albumin microbubbles with a concentration of 4 x 10(8) microbubbles/ml and a diameter of 4 +/- 1 mu. RESULTS: Antegrade cardioplegia was not associated with aortic regurgitation in 23 of 40 (58%) patients. Seven patients (17%) had only mild aortic regurgitation, four patients (10%) had moderate regurgitation, and six (15%) had severe aortic regurgitation. The percent of myocardial opacification was 76.0 +/- 10.5 in the 23 patients who did not have aortic regurgitation, 76.0 +/- 17.0 in the 7 patients who had mild regurgitation, 52.5 +/- 18.1 in the 4 patients who had moderate regurgitation, and 48.5 +/- 18.3 in 6 patients who had severe aortic regurgitation (Kruskal-Wallis stat, 12.9; P < 0.005). Retrograde cardioplegia was not associated with right-to-left shunt in 11 of 22 patients (50%). In seven patients (32%), there was only a mild passage of contrast material to the left atrium. In the remaining four patients (18%), there was a moderate (one patient) to severe (three patients) right-to-left shunt at the level of the fossa ovalis. CONCLUSIONS: This study shows that incomplete myocardial distribution of cardioplegia, secondary to transient aortic valve incompetence or shunting through the foramen ovale, is not uncommon in patients undergoing coronary surgery.

[Anterograde and retrograde cardioplegia in myocardial revascularization. An intraoperative contrast echographic study]. / Cardioplegia anterograda e retrograda nella rivascolarizzazione miocardica. Studio ecocontrastografico intraoperatorio.

The aim of this study was to assess the distribution of antegrade and retrograde cardioplegia with intraoperative contrast echocardiography in patients undergoing coronary artery bypass grafting. Fifteen patients with chronic stable angina pectoris and severe coronary artery disease were studied. The severity of coronary artery disease was assessed at coronary angiography, using the Jeopardy Score System. The presence and the extent of collateral circulation was evaluated on the basis of preoperative coronary angiography and graded as: absent or poor; good or excellent. Coronary revascularization was carried out during extracorporeal circulation and myocardial protection was performed with antegrade (aortic root) and retrograde (right atrial) cardioplegia. The echo contrast agent was sterilely prepared 1 hour prior to surgery and consisted of a solution of sonicated 5% human albumin microbubbles. Two ml of sonicated albumin were injected along with antegrade cardioplegia and 4 ml with retrograde cardioplegia. The echocardiographic images were obtained with transesophageal echocardiography in the transgastric left ventricular short-axis view. Images were recorded on videotape for off-line planimetric measurement of percent myocardial opacification. Data were analyzed with the analysis of variance. Multiple comparisons were made with Student's paired t test and using Bonferroni's correction. Myocardial opacification was 58.9 +/- 12.9% during antegrade cardioplegia and 77.5 +/- 16.4% during retrograde cardioplegia (p = 0.003). This overall difference was mainly due to the impact of collateral circulation in the distribution of antegrade cardioplegia. Patients with absent or poor collateral circulation showed a lower degree of myocardial opacification than patients with good or excellent myocardial opacification (44.3 +/- 12.0% versus 64.2 +/- 8.6%; p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

[The identification of vital myocardium with the dopamine stimulation test: an intraoperative echocardiographic study]. / Identificazione del miocardio vitale con test di stimolazione con dopamina: studio ecocardiografico intraoperatorio.

The aim of this study was to detect by dopamine echocardiography dysfunctioning but viable myocardial segments. We have studied 19 patients with 3-vessel disease and chronic, stable angina pectoris. Patients were studied by intraoperative transesophageal echocardiography during coronary artery bypass surgery. The analysis of regional systolic function was performed utilizing the transgastric short-axis view at papillary muscle level and dividing the left ventricle in 8 segments, according to the recommendations of the American Society of Echocardiography. A total of 152 myocardial segments were analyzed. Percent systolic wall thickening was calculated in each segment at baseline (early after pericardiectomy), during dopamine infusion (5 mcg/kg/min) and 30 min after separation from cardiopulmonary bypass (after protamine administration). The administration of vasodilatory or inotropic drugs was avoided. The echocardiographic images were recorded on videotape and analyzed off-line by 2 independent observers. Segments showing at baseline percent systolic wall thickening < 30% were considered dysfunctional (134/152 = 88%). Eighty-four (63%) of these segments, increasing during dopamine infusion percent systolic wall thickening > 10% (from 12.9 +/- 3.5 to 20.7 +/- 5.4%; p < 0.05) were considered responder. On the other hand, 50 segments (37%) showing during dopamine an increment in percent systolic wall thickening < 10%, were considered non-responder. After coronary surgery, responder segments showed a significant increase in percent systolic wall thickening in comparison with baseline values (from 12.9 +/- 3.5 to 22.1 +/- 4.3%; p < 0.05). Segments non-responding to dopamine showed no significant changes in percent systolic wall thickening after myocardial revascularization.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative contrast echocardiography for assessment of the surgical repair of coronary artery fistula.

We report two cases of acquired coronary fistula in whom fistula flow and surgical repair were evaluated intraoperatively by contrast echocardiography. Surgical repair was carried out through the left atrium because of the associated surgical procedure on the mitral valve. Contrast echocardiography allowed easy identification of the fistula openings in the left atrium and intraoperative control of the efficacy of the surgical closure. Contrast echocardiography is an ideal tool for the intraoperative diagnosis of effective interruption of a coronary fistula.

Echocardiographic analysis of dysfunctional and normal myocardial segments before and immediately after coronary artery bypass graft surgery.

Echocardiography has revealed evidence of "subnormal" regional contraction patterns that result from myocardial ischemia and are often accompanied by nonadjacent "hyperkinetic" regions. Whether these regions of hyperkinetic wall motion persist unchanged or revert to normal after coronary artery bypass graft (CABG) surgery has not been studied in humans. Using echocardiography, we evaluated both dysfunctional and normal myocardial regions for changes in segmental wall motion and percent of systolic wall thickening that occurred immediately after CABG surgery in 32 patients. Segmental wall motion analysis before CABG surgery in these patients revealed that 170 (66%) of 256 myocardial segments were subnormal, of which 115 (67%) improved and 102 (60%) returned to normal immediately after CABG surgery. Eleven myocardial segments that were hyperkinetic before CABG surgery returned to normal after CABG surgery. Preoperatively, 162 (63%) of 256 myocardial segments had systolic wall thickening less than 30%, which increased from 11.8% +/- 8.9% to 24.3% +/- 14.3% (mean +/- SD) (P less than 0.01) postoperatively. Conversely, a reverse trend was found when systolic wall thickening was greater than 30% before CABG surgery: thickening decreased from 46.2% +/- 13.8% to 33.4% +/- 14.8% after CABG surgery (P less than 0.01). Thus, we conclude that immediately after CABG surgery, there is a recovery of function in some myocardial segments and a reduction in function in others. Furthermore, we conclude that the semiquantitative assessment of percent of systolic wall thickening is a more reliable (consistent) echocardiographic index of myocardial function compared with the qualitative assessment of segmental wall motion immediately after CABG surgery.

Reversal of left ventricular dysfunction early after coronary artery bypass grafting.

This study evaluated the early effect of coronary artery bypass grafting (CABG) on left ventricular systolic function. Intraoperative echocardiography was performed in 32 patients with coronary artery disease and chronic, stable angina pectoris. Left ventricular short-axis images at mid-papillary muscle level were videotaped at similar loading conditions shortly after pericardiotomy and 28 +/- 5 min after weaning from cardiopulmonary bypass. Inotropic or vasodilator administration was avoided or suspended at least 5 min before echocardiography. The left ventricle was divided off-line into 8 segments. The ejection fraction and percent systolic wall thickening (PSWT) were calculated pre- and post-CABG. A total of 256 myocardial segments were analyzed. Any segment showing a preoperative PSWT of less than 30% was considered dysfunctional, while segments with a PSWT of greater than 30% were considered normal. After surgery, the PSWT in 162 dysfunctional segments (63%) increased from 11.8 +/- 8.9 to 24.3 +/- 14.3% (p less than 0.001). Conversely, a reverse trend was found in the remaining 94 normal segments (37%) with a decreasing PSWT from 46.2 +/- 13.8 to 33.4 +/- 14.8% (p less than 0.001). Ejection fraction also increased from 47.2 +/- 3.5 to 58.5 +/- 18.9% (p less than 0.05). Thus, CABG is followed by an immediate recovery of systolic function in dysfunctional myocardial segments, while compensatory hyperfunction is reduced in normal segments. These results indicate that the post-CABG improvement in PSWT is due to redistribution of coronary blood flow, rather than to pharmacological or hormonal influences. Intraoperative echocardiography is a useful technique to monitor left ventricular function during surgery.

Spontaneous left atrial echocardiographic contrast in mitral stenosis: early disappearance after valve replacement.

We describe a patient with mitral stenosis and severely enlarged left atrium. Transthoracic echocardiography showed a false image of intraatrial thrombus, whereas transesophageal echocardiography showed massive spontaneous left atrial contrast. Intraoperative transesophageal echocardiography was performed. During cardioplegic arrest the contrast was enhanced, but it gradually and completely cleared 15 minutes after cardiopulmonary by-pass arrest. Transesophageal echocardiography is a useful technique for the study of intraatrial masses and may bring a new dimension to tissue characterization studies.

Ventricular conduction defects and atrial fibrillation after coronary artery bypass grafting. Multivariate analysis of preoperative, intraoperative and postoperative variables.

Preoperative, intraoperative and postoperative variables, which might play a role in the development of ventricular conduction defects (VCD) and atrial fibrillation (AF) following coronary artery bypass grafting (CABG), were evaluated in 236 consecutive patients. VCD and AF developed postoperatively in 15.5% of patients: 4.5% had VCD (subgroup A), 11.0% had AF (subgroup B). In 84.5% of patients VCD and AF did not occur (subgroup C). Univariate analysis showed statistically significant differences between subgroups A and C with respect to: left main significant stenoses and number of diseased vessels. Bypass pump time and aortic cross-clamp time were significantly longer in subgroup B. Multivariate analysis showed a significantly greater incidence of left main disease and of right coronary artery occlusion associated with significant stenosis of the proximal left anterior descending artery in subgroup A. In subgroup B, the duration of aortic cross-clamp time was significantly higher. Ischaemic injury, with increasing duration of cardioplegic arrest, seems to play a key role in the development of AF. Nonhomogeneous cardioplegic delivery to critical areas of myocardium, and particularly to the specialized conducting system, may cause VCD after CABG.

Effects of uncomplicated coronary artery bypass graft surgery on global and regional left ventricular function at rest. Study by equilibrium radionuclide angiocardiography.

To evaluate the effects of uncomplicated revascularization surgery on resting global and regional left ventricular function we studied 34 patients, enrolled consecutively, by radionuclide angiocardiography. After surgery, we found no significant change in global left ventricular ejection fraction; this was true even in the subgroup of 14 patients who developed paradoxical septal motion. This finding indicates that the development of paradoxical septal motion after uncomplicated cardiac surgery does not compromise global left ventricular function. Both in the subgroup of patients with paradoxical septal motion and in the subgroup without paradoxical septal motion regional ejection fraction calculations showed the same postoperative pattern consisting of increase of the proximal and distal posterolateral regional ejection fraction, increase in the inferoapical regional ejection fraction and unchanged proximal and distal septal regional ejection fraction. In our patients paradoxical septal motion is not due to pericardial effusion, conduction disturbance, septal ischemia or infarction. Our data suggest that the anteromedial translation of the entire heart during systole, due to surgical removal of constraints, may account for both the false improvement of posterolateral and inferoapical regional wall motion and the development of paradoxical septal motion.

Surgical risk factors in total anomalous pulmonary venous connection.

Eighty-three patients underwent surgical correction of total anomalous pulmonary venous connection (TAPVC) between 1973 and 1986. There were 46 boys and 37 girls. Median age at operation was 60 days (1 to 240) and median weight 3.9 kg (1 to 22). The anatomic types encountered included infracardiac connection (16 patients), supracardiac connection (32) and pulmonary venous drainage connected directly to the coronary sinus (27). Mixed anomalous drainage or pulmonary venous return connected directly to the right atrium occurred in 8 patients. Diagnosis was established by cardiac catheterization and angiography (56 patients), clinical examination (3) and cross-sectional echocardiography alone in 24 of the last consecutive 28 patients. Pulmonary hypertension was present in 26 (55%) of those who underwent cardiac catheterization. The median pulmonary vascular resistance was 4.2 units/m2 (body surface area) for all the patients, whereas in those with infracardiac pulmonary venous connection the median value was 10 units/m2. The median interval between admission and operation was 72 hours. Surgical correction was performed using profound hypothermia and circulatory arrest in 68; for the remainder, conventional cardiopulmonary bypass with profound to moderate hypothermia was used. Ten patients developed 1 or more pulmonary hypertensive crises during the early postoperative period. These were diagnosed in 8 by direct pulmonary artery pressure measurement and in 2 by clinical examination. Late reoperation was necessary in 6 patients (10%). Analyses of risk factors for 30-day survival for all patients showed that the risk of early death was associated with the type of anomaly (infradiaphragmatic), occurrence of pulmonary hypertensive crises, year of the operation, set of the patient and pressure of preoperative congestive heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)